package com.bianxingji.utils;

import java.io.IOException;
import java.util.Arrays;
import java.util.Base64;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Base64 工具类
 */
public class Base64Util {
    private static final char last2byte = (char) Integer.parseInt("00000011", 2);
    private static final char last4byte = (char) Integer.parseInt("00001111", 2);
    private static final char last6byte = (char) Integer.parseInt("00111111", 2);
    private static final char lead6byte = (char) Integer.parseInt("11111100", 2);
    private static final char lead4byte = (char) Integer.parseInt("11110000", 2);
    private static final char lead2byte = (char) Integer.parseInt("11000000", 2);
    private static final char[] encodeTable = new char[]{'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'};

    public Base64Util() {
    }

    public static byte[] decodeBase64ToImage(String base64String) throws IOException {

        if (base64String.contains("data:")) {
            int start = base64String.indexOf(",");
            base64String = base64String.substring(start + 1);
        }
        base64String = base64String.replaceAll("\r|\n", "");
        base64String = base64String.trim();
        return Base64.getDecoder().decode(base64String);
    }

    public static String encode(byte[] from) {
        StringBuilder to = new StringBuilder((int) ((double) from.length * 1.34D) + 3);
        int num = 0;
        char currentByte = 0;

        int i;
        for (i = 0; i < from.length; ++i) {
            for (num %= 8; num < 8; num += 6) {
                switch (num) {
                    case 0:
                        currentByte = (char) (from[i] & lead6byte);
                        currentByte = (char) (currentByte >>> 2);
                    case 1:
                    case 3:
                    case 5:
                    default:
                        break;
                    case 2:
                        currentByte = (char) (from[i] & last6byte);
                        break;
                    case 4:
                        currentByte = (char) (from[i] & last4byte);
                        currentByte = (char) (currentByte << 2);
                        if (i + 1 < from.length) {
                            currentByte = (char) (currentByte | (from[i + 1] & lead2byte) >>> 6);
                        }
                        break;
                    case 6:
                        currentByte = (char) (from[i] & last2byte);
                        currentByte = (char) (currentByte << 4);
                        if (i + 1 < from.length) {
                            currentByte = (char) (currentByte | (from[i + 1] & lead4byte) >>> 4);
                        }
                }

                to.append(encodeTable[currentByte]);
            }
        }

        if (to.length() % 4 != 0) {
            for (i = 4 - to.length() % 4; i > 0; --i) {
                to.append("=");
            }
        }

        return to.toString();
    }

    /**
     * 提取 Base64 字符串中的 MIME 类型（例如 image/png）
     */
    public static String extractFileType(String base64Data) {
        String regex = "data:(.*?);base64,"; // 匹配 data:image/png;base64,...
        Pattern pattern = Pattern.compile(regex);
        Matcher matcher = pattern.matcher(base64Data);
        if (matcher.find()) {
            return matcher.group(1);  // 返回 MIME 类型
        }
        return null;
    }


    public static void main(String[] args) {
        int b[]={3,1,5,7,9,12};
        int y=0;
        for(int i=0;i<b.length;i++){
            for(int j=0;j<b.length-1-i;j++){
                if(b[j]>b[j+1]){
                    int t=b[j];
                    b[j]=b[j+1];
                    b[j+1]=t;
                }
                y++;
            }
        }
        System.out.println("执行了"+y+"次");
        System.out.println(Arrays.toString(b));
        /*将base64z转成图片保存*/
//        String base64String = "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/wcAAwAB/Orgxu4AAAAASUVORK5CYII=";
//
//        String outputFilePath = "D://java//output.png";
//
//        try {
//            decodeBase64ToImage(base64String, outputFilePath);
//            System.out.println("图片保存成功！");
//        } catch (IOException e) {
//            System.out.println("解码失败：" + e.getMessage());
//        }
    }
}
